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H Gewurz

Publications and source records attributed to H Gewurz.

At least 55 records · Page 3Linked to original sources
PubMed1986

Aggregated C-reactive protein binds to human polymorphonuclear leukocytes and potentiates Fc receptor-mediated chemiluminescence.

Aggregated C-reactive protein (CRP), an acute phase reactant, binds to and influences the functional activities of human mononuclear leukocytes. Our purpose was to examine the potential interactions between CRP and human polymorphonuclear leukocytes (PMNL). Binding of CRP to PMNL was examined by flow cytometry after cell incubation with fluorescein-labeled heat-aggregated CRP (Agg-CRP) or Agg-CRP and fluorescein-conjugated F(ab')2 anti-CRP antibodies. It was determined that, at an optimal dose of Agg-CRP (100 micrograms), approximately 36% of PMNL were fluorescence positive. This was in contrast to the 70% of monocytes and 8% of lymphocytes that expressed Agg-CRP binding sites. Although less than half of resting PMNL bound Agg-CRP, up to 93% of PMNL activated with 1.0 micrograms/ml of phorbol myristate acetate (PMA) expressed binding sites for Agg-CRP. Exposure to PMA similarly enhanced the amount of Agg-CRP bound per PMNL as determined by mean channel fluorescence. To evaluate whether Agg-CRP binding to PMNL could induce or modify a biologic response, respiratory burst activity was assessed by measuring luminol-enhanced chemiluminescence. Whereas Agg-CRP alone did not elicit a chemiluminescence response, Agg-CRP synergistically enhanced the chemiluminescence response induced by heat-aggregated IgG (Agg-IgG). Although this enhancing effect of Agg-CRP could be observed at both optimal and suboptimal concentrations of Agg-IgG, no enhancement of PMA or serum-opsonized zymosan-induced CL was detected. These data demonstrate that aggregated CRP binds to and selectively modulates the response of PMNL to Fc receptor-mediated activation.

C-Reactive Protein↗
PubMed1985

Effect of divalent metal ions and pH upon the binding reactivity of human serum amyloid P component, a C-reactive protein homologue, for zymosan. Preferential reactivity in the presence of copper and acidic pH.

The serum amyloid P component (SAP) has been found to associate in vitro with a variety of polysaccharide and proteinaceous ligands including the yeast cell wall polysaccharide preparation, zymosan, in the presence of calcium at neutral pH. In the present study, we have investigated the role of copper and zinc and other divalent cations and acidic pH on the binding of SAP to zymosan. We report that binding occurs not only in the presence of calcium, but in the presence of copper, zinc, and cadmium as well. No binding occurs in the absence of added metal, or in the presence of barium, cobalt, magnesium, manganese, or nickel. 125I-SAP binding in the presence of metals is inhibited by presaturating the zymosan surface with unlabeled SAP. Whereas calcium-mediated binding decreases by more than 50% as the pH is lowered to 5, copper-mediated binding increases substantially at the more acidic pH values while zinc-mediated binding is essentially unchanged. These data indicate that, in addition to calcium at neutral pH, copper (and zinc) at neutral and particularly acidic pH values mediates SAP binding to polysaccharide ligands. This suggests that SAP may well be considered a copper- as well as a calcium-dependent protein under certain conditions and that this reactivity is favored under those conditions of lowered pH which may result from metabolic processes occurring at local sites of inflammation.

Amyloid↗
PubMed1984

C-reactive protein inhibits pneumococcal activation of the alternative pathway by increasing the interaction between factor H and C3b.

We previously studied two alternative pathway activators, Streptococcus pneumoniae and positively charged liposomes, which react with C-reactive protein (CRP). Binding of CRP to these surfaces initiates classical pathway but blocks alternative pathway activation. In this study, we investigated the mechanism of this inhibition using S. pneumoniae, R36a. R36a were pretreated with CRP (CRP-R36a) or buffer and incubated with C2-deficient human serum to which 125I-labeled C3 had been added. The amount of specific 125I-C3 binding was decreased from 8200 mol/CFU on R36a to 2200 mol/CFU on CRP-R36a. In contrast, when the same experiment was performed with purified factors B, D, P, and C3, in the absence of regulatory proteins, specific 125I-C3 uptake was slightly lower on R36a (6100 mol/CFU) than on CRP-R36a (8100 mol/CFU). The ability of the fixed C3b to inactivate factor B in the presence of factor D was equivalent on the two surfaces. The binding of the regulatory factor H to C3b fixed to R36a and CRP-R36a was compared by using purified 125I-labeled factor H. The ratio of factor H bound to C3 bound was twofold greater on CRP-R36a than on R36a. This increase was found by using C2-deficient serum or purified factors B, D, P, and C3 to fix C3b to the surfaces. The ability of CRP to inhibit C3 binding to R36a was restored by the addition of factors H and I to factors B, D, P, and C3. These results indicate that CRP inhibits alternative pathway activation by increasing regulation of bound C3.

Binding, Competitive↗
PubMed1984

Inhibition of neutrophil activation by alpha1-acid glycoprotein.

We report that alpha1-acid glycoprotein (AAG), a naturally occurring human plasma protein and acute phase reactant of uncertain biological function, inhibits human neutrophil aggregation and superoxide anion generation induced by a variety of stimuli including zymosan treated serum, formyl-methionyl-leucyl-phenylalanine and phorbol myristate acetate. Inhibition was transient, directly proportional to the glycoprotein concentration and inversely proportional to the concentration of the stimulus added. Desialyzation, resulting in the removal of a substantial portion of the molecule's negative charge, did not alter the effectiveness of AAG. Removal of the penultimate galactose residues from desialyzed AAG resulted in a slight but significant reversal of inhibition, suggesting that the heteropolysaccharide units of AAG may be important for inhibition of cellular function. We therefore suggest that the acute phase glycoprotein AAG may be a significant modulator of neutrophil as well as platelet and lymphocyte function during inflammation.

Cell Aggregation↗
PubMed1984

Inhibition of antibody responses to phosphocholine by C-reactive protein.

C-reactive protein (CRP) is an acute phase serum protein in man that binds to the cell wall C-polysaccharide (PnC) of Streptococcus pneumoniae via phosphocholine (PC) determinants. We have previously shown that in mice CRP increases splenic clearance of PnC-coated autologous erythrocytes and S. pneumoniae, and increases survival after pneumococcal infection. Because CRP alters clearance of particulate PnC antigens, we tested its effect on immunization with pneumococci. Pretreatment of mice with 50 to 200 micrograms CRP 30 min before immunization with serotype 3 S. pneumoniae resulted in dose-dependent inhibition of the antibody response to PC. Both serum hemagglutinin and splenic PFC against PC were decreased in CRP-treated mice tested from 1 to 10 days after injection of antigen. CRP treatment had no effect on the antibody response to the serotype 3 capsular polysaccharide, another T-independent antigen. To determine whether CRP inhibition was related to altered processing of particulate antigen, mice were immunized with horse red blood cells (HRBC) conjugated with PC or PnC and the PFC responses to PC and HRBC were determined. CRP treatment resulted in specific inhibition of the PFC response to PC in both cases without affecting the response to HRBC. These results indicate that inhibition of the antibody response by CRP is not the result of altered antigen localization and processing, and that CRP may prevent immunization by masking determinants on bacterial or other surfaces.

Animals↗
PubMed1984

Assay, purification and further characterization of 7S C1q-precipitins (C1q-p) in hypocomplementemic vasculitis urticaria syndrome and systemic lupus erythematosus.

C1q-precipitins (C1q-p) are comprised of 7S IgG with C1q-binding activity found in sera of patients with hypocomplementemic vasculitis urticaria syndrome ( HVUS ) and systemic lupus erythematosis (SLE). We have utilized C1q-coated polystyrene beads to selectively isolate C1q-p and to establish a sensitive and quantitative assay of C1q-p and immune complex activity. Purified C1q-p was comprised of polyclonal IgG which retained 7S sedimentation and solid phase C1q-binding activity at physiological ionic strength both in the presence and absence of normal human sera. No precipitation interaction was observed between C1q-p and fluid-phase C1q or C1 under the conditions tested. Purified C1q-p had no activity in the Raji cell immune complex activity. C1q-p activity also was observed in and purified from SLE serum; this activity was distinguishable from 7S immune complex activity detected by Raji cells which was also present in SLE serum. These studies indicate that C1q-p is a 7S IgG molecule found in HVUS as well as some SLE sera and has activity in C1q-binding but not in Raji cell-binding immune complex assays. These data also suggest that C1q-p is a monomeric, polyclonal IgG with preferential affinity for bound C1q. In addition to its potential role in immune complex disease, C1q-p may also provide an important tool for studying the interaction of immunoglobulin and C1q, and should contribute important information to understanding the pathobiology of immune complex disease.

Antigen-Antibody Complex↗
PubMed1984

Binding of C-reactive protein to the pneumococcal capsule or cell wall results in differential localization of C3 and stimulation of phagocytosis.

C-reactive protein (CRP) is a serum protein that shows rapid increases of as much as 1000-fold in concentration in response to infection, traumatic injury, or inflammation. CRP reacts with the phosphocholine moiety of pneumococcal cell wall C-polysaccharide, and this reaction can lead to complement activation in vitro and protection against pneumococcal infection in vivo. We have previously studied the chemiluminescence response of human neutrophils to Streptococcus pneumoniae as a measure of in vitro opsonophagocytosis by CRP and complement. CRP in the presence of complement was an effective opsonin for S. pneumoniae serotype 27 (Pn27), but not for serotypes 3 or 6. Because Pn27 differs from most serotypes of S. pneumoniae in containing phosphocholine in its capsular polysaccharide, we have determined the sites of CRP and C3 fixation to Pn27 and S. pneumoniae serotype 4 (Pn4), and related these to the ability of CRP and complement to opsonize these serotypes in vitro. By using a chemiluminescence (CL) assay to measure opsonophagocytosis, CRP was shown to enhance the response of human neutrophils and monocytes to Pn27 in the presence of normal human serum. The CL response of neutrophils and monocytes to Pn4 was not affected by the addition of CRP to serum. The addition of anti-capsular antibody to Pn4 and Pn27 enhanced the CL responses of both neutrophils and monocytes to both bacteria. The localization of bound CRP and C3 on Pn4 and Pn27 was determined by immunoelectron microscopy. CRP bound to Pn4 only in the cell wall region and C3 was located in this area whether or not CRP was present. Anti-capsular antibody deposited C3 in the capsule of Pn4. In contrast, Pn27 bound CRP throughout the capsule and cell wall areas. C3 was deposited in the cell wall region of Pn27 by serum alone and in the cell wall region and capsule when CRP or anti-capsular antibody was present. Because C3 fixation to the capsule was consistently associated with enhanced responses by phagocytic cells, it appears that the site of CRP binding and subsequent complement activation may be critical in the opsonophagocytosis of S. pneumoniae. These findings extend the correlation between capsular C3 and opsonization to a nonimmune system. By using CRP and different pneumococcal serotypes we have shown that the same molecules that are effective in the stimulation of phagocytic cells when bound to the capsule are not effective when bound to the cell wall.

Animals↗
PubMed1983

Possible role for C-reactive protein in the human natural killer cell response.

Functional NK activity can be removed from human PBL and from phagocyte- and T cell-depleted LGL preparations by treatment with antisera specific for C-reactive protein (CRP) in the presence of complement (C). Pretreatment of NK effector cells with high concentrations of anti-CRP in the absence of C also depletes functional activity. These results indicate that CRP or an antigenically similar molecule is present on a population of NK effector cells. Fluorescent antibody studies in which biotin-avidin amplification was used confirm the presence of surface CRP (S-CRP) on a small percentage of nonphagocytic peripheral blood mononuclear cells. S-CRP readily caps off, which suggest that removal by capping obviates killing by this cell population. This indicates that S-CRP or a molecule that co-caps with S-CRP may be required for successful effector-target cell interaction. The addition of exogenous CRP or CRP-CPS complexes, however, does not alter NK responses. A subpopulation of lymphoid cells responsible for functional NK activity therefore appears to bear surface CRP.

C-Reactive Protein↗
PubMed1983

Meningococcal meningitis in a women with inherited deficiency of the ninth component of complement.

A 17-year-old woman presented with acute pyogenic meningitis; Neisseria meningitidis group C was isolated from blood on culture. Complement assays demonstrated a hemolytic complement titer of 12 u/ml; individual components were normal except for C9, which was absent by both functional and antigenic analysis. Family studies were consistent with a familial C9 deficiency, autosomal co-dominant inheritance. This is the first report of the association of C9 deficiency and disseminated neisserial infection; whether this complement deficiency predisposes to the neisserial infection remains to be established.

Adolescent↗
PubMed1983

Influence of heparin on interactions between C-reactive protein and polycations.

C-reactive protein (CRP) is a trace serum protein which elevates up to 1000-fold in concentration in association with inflammation and tissue necrosis. CRP binds with phosphocholine and phosphate esters; initiates reactions of agglutination, opsonization and complement consumption; and precipitates with protamine and synthetic polymers of lysine and arginine, and these reactivities are modulated by calcium and phosphocholine. We now report on the interactions of heparin with these polycations in the absence and presence of CRP, which show marked similarities to reactions between antigen and antibody. Heparin optimally precipitated with the polycations over a narrow range of reactant ratios, peaking at slight anion charge excess. The complexes formed did not dissociate in excess heparin: however, complex formation was significantly depressed when heparin was added in a single dose in excess of the amount required for optimal precipitation. Calcium did not affect the precipitation of heparin with polycation, and heparin did not precipitate with CRP. However, heparin did induce a rapid and efficient dissociation of CRP-polycation precipitates preformed at equivalence, with total release of CRP. Small amounts of heparin augmented precipitation under conditions of polycation excess of CRP, but as heparin levels were increased to amounts needed to reach equivalence with polycation, CRP was resolubilized in favor of the preferred heparin-polycation complexes. Chondroitin sulfate was similar to heparin in its effects upon the CRP-poly-L-arginine (PLA) interaction, while hyaluronic acid enhanced CRP-PLA precipitation at all concentrations tested and DNA had neither augmenting nor solubilizing effects. These data indicate that CRP-polycation interactions are significantly and selectively influenced in the presence of small amounts of heparin and certain other polyanions. This modulatory reactivity may be of importance in the biological reactivities of CRP during episodes of acute inflammation.

C-Reactive Protein↗
PubMed1983

Antigenic, electrophoretic and binding alterations of human C-reactive protein modified selectively in the absence of calcium.

C-Reactive protein (CRP) is a trace component of normal human serum which has a mol. wt of 105,000 and is composed of five apparently identical subunits arranged in cyclic symmetry. The serum concentration of this protein is known to increase dramatically in response to acute inflammatory or necrotic processes. We report here that in the presence of high concentrations of urea significant antigenic, electrophoretic and binding site modifications of CRP occur selectively in the absence of calcium. CRP treated in this way (designated F-CRP) had a pI of 5.4 and alpha-electrophoretic mobility in contrast to the native molecule which had a pI of 6.4 and gamma-mobility. F-CRP retained a partial antigenic identity to native CRP, displayed decreased intrinsic tryptophan fluorescence, and expressed a new antigenic reactivity. A similar neoantigen was expressed by heating CRP selectively in the absence if calcium (63 degrees C, 5 min). Treatment with guanidinium-HCl or deliberate carbamylation did not produce F-CRP or the expression of the F-antigen. The formation of F-CRP in urea or by heat was prevented by the presence of 0.7 mM or more calcium. CRP treated in this way retained identical characteristics to native CRP. F-CRP chromatographed through Sephadex G-150 in the presence or absence of 6M urea as a protein of apparent mol. wt 75, 000 with no evidence for free CRP subunits. The formation of F-CRP from native CRP resulted in a loss of capacity for calcium-dependent binding to the C-polysaccharide despite the persistence of calcium-independent binding reactivity for polycations. These data suggest that in the presence of sufficient calcium CRP can resist urea- or heat-induced structural denaturation, maintaining antigenic, electrophoretic and binding identity to the native molecule. In the absence of calcium, exposure to urea led to increased electrophoretic mobility and exposure of a new antigenic reactivity, and to alterations in the phosphocholine- but not the polycation-binding sites of the native CRP molecule; this new antigenic reactivity may be of value in further studies on the CRP molecule.

Antigens↗
PubMed1983

Effects of heparin and alpha 1-acid glycoprotein on thrombin or Activated Thrombofax Reagent-induced platelet aggregation and clot formation.

alpha 1-Acid glycoprotein (AAG) obtained from ascites and/or pleural fluids exhibited anti-heparin effects in platelet-poor plasma when evaluated by activated partial thromboplastin (Activated Thrombofax Reagent) and heparin-thrombin clotting time assays. An anti-heparin effect for AAG was also demonstrable in platelet-rich plasma (PRP) challenged with thrombin, but only over a limited range of heparin concentrations; at elevated heparin concentrations, and only in the presence of AAG, both platelet aggregation and clot formation were substantially inhibited. However, no detectable anti-heparin effect was observed following challenge of PRP with Activated Thrombofax Reagent; indeed, the anti-coagulant effect of heparin appeared synergistically amplified in these systems containing AAG, and AAG exhibited platelet pro-aggregate and pro-coagulant properties in the absence of heparin. The platelet pro-aggregating activity of AAG, though independent of heparin, appeared to require the onset of the coagulation cascade prior to the generation of thrombin; in the absence of such initiation, AAG remained a potent inhibitor of platelet activation.

Blood Coagulation↗
PubMed1983

Neoantigen of the polymerized ninth component of complement. Characterization of a monoclonal antibody and immunohistochemical localization in renal disease.

A monoclonal antibody to a neoantigen of the C9 portion of the membrane attack complex (MAC) of human complement has been developed and characterized. The distribution of this neoantigen was assessed by indirect immunofluorescence microscopy in nephritic and nonnephritic renal diseases. The antibody (Poly C9-MA) reacted on enzyme-linked immunosorbent assay (ELISA) with a determinant in complement-activated serum that was undetectable in normal human serum (NHS). Zymosan particles incubated in NHS had positive immunofluorescent staining with Poly C9-MA; however, binding of Poly C9-MA was not observed with zymosan particles incubated in sera deficient in individual complement components C3, C5, C6, C7, C8, or C9. Reconstitution of C9-deficient sera with purified C9 restored the fluorescence with Poly C9-MA. Poly C9-MA reacted positively by ELISA in a dose-dependent manner with purified MC5b-9 solubilized from membranes of antibody-coated sheep erythrocytes treated with NHS but not with intermediate complement complexes. Poly C9-MA also reacted in a dose-dependent manner on ELISA and in a radioimmunoassay with polymerized C9 (37 degrees C, 64 h) (poly C9) but not with monomeric C9. Increasing amounts of either unlabeled poly C9 or purified MC5b-9 inhibited the 125I-poly C9 RIA in an identical manner. These studies demonstrate that Poly C9-MA recognizes a neoantigen of C9 common to both the MAC and to poly C9. By immunofluorescence, Poly C9-MA reacted minimally with normal kidney tissue in juxtaglomerular loci, the mesangial stalk, and vessel walls. Poly C9-MA stained kidney tissue from patients with glomerulonephritis in a pattern similar to that seen with polyclonal anti-human C3. In tissue from patients with nonnephritic renal disease--diabetes, hypertension, and obstructive uropathy--Poly C9-MA was strongly reactive in the mesangial stalk and juxtaglomerular regions, tubular basement membranes, and vascular walls. Poly C9-MA binding was especially prominent in areas of advanced tissue injury. Poly C9-MA frequently stained loci where C3 was either minimally present or absent. These studies provide strong evidence for complement activation not only in nephritic but also in nonnephritic renal diseases.

Adult↗
PubMed1983

Effects of C-reactive protein on human lymphocyte responsiveness.

C-reactive protein (CRP), a trace serum protein that increases markedly in concentration during inflammatory reactions, was recently shown to bind to a subset of human IgG-FcR-bearing peripheral blood lymphocytes in the presence of a ligand such as pneumococcal C-polysaccharide (CPS). CRP has also been detected on a small percentage of PBL that are associated with NK activity. In the present study, we assessed the effects of CRP and CRP-CPS complexes on a variety of human lymphocyte functions in vitro. CRP and CRP complexes significantly enhanced (generally two to threefold) cell-mediated cytotoxicity, minimally enhanced the MLC reaction, and induced a small but regularly detectable blastogenic response in resting PBL. CRP or CRP-CPS complexes had no effect on mitogen-induced blastogenesis, PWM-induced generation of IgM plaque-forming cells, E-rosette formation, antibody-dependent cell-mediated cytotoxicity, or NK activity. The basis for the preferential ability of CRP to enhance cytotoxicity responses in vitro is under further investigation.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1983

C-reactive protein antigenicity on the surface of human lymphocytes.

We reported previously that C-reactive protein (CRP), when complexed to a multivalent binding specificity, can bind to a subset of lymphocytes that bear the IgG Fc receptor. Recently we showed that anti-CRP plus complement depletes natural killer function. We now show the detection of CRP on the surface (S-CRP) of a small percentage of PBL and on a minor population of phagocytic mononuclear cells. S-CRP is not detectable by direct immunofluorescence, but is readily discernible by using more sensitive techniques such as biotinylated anti-CRP with fluorescent avidin or indirect immunofluorescence with monoclonal anti-CRP. S-CRP is expressed in the absence of calcium, whereas the binding of complexed CRP is calcium dependent. S-CRP does not appear to be the exclusive binding site for CRP-CPS because anti-CRP does not block the binding of complexed CRP. Both the binding site for complexed CRP and S-CRP can be capped off; however, the kinetics of capping of these two surface molecules is different. Cells binding complexed CRP are OKT11-, whereas a significant number of PBL bearing S-CRP are OKT11+. Therefore cells bearing S-CRP appear to be a separate population from those that bind complexed CRP. These studies establish the presence of S-CRP on a subpopulation of lymphocytes, define conditions required for its detection, and speak to certain of the relationships between S-CRP and the binding site of CRP-CPS complexes.

Antibodies, Monoclonal↗